Electric Drive Stall Torque Enhancement via Vehicle Inputs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrified powertrains in vehicles face challenges in optimizing low-speed electric drive performance, particularly in situations where increased stall torque is needed without compromising noise, vibration, and harshness (NVH) performance or risking damage to sensitive powertrain hardware.
Innovation Solution
A real-time controller-based method that adjusts default electric stall torque limits and selects appropriate inverter control strategies, including pulse width modulation (PWM) types and frequencies, based on vehicle-level inputs to temporarily increase stall torque limits while maintaining NVH performance and adhering to thermal limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If default electric stall torque limits are increased to enhance low-speed performance, then stall torque capability is improved, but thermal limits of powertrain hardware may be violated
Solution Approach 1:
The system dynamically adjusts electric stall torque limits in real-time based on operating conditions, vehicle level inputs, and thermal states rather than using fixed limits. The controller monitors thermal conditions and dynamically modifies torque limits to allow temporary enhancement when safe, while preventing violations when thermal limits are approached
Solution Approach 2:
The system changes the parameter of electric stall torque limits based on multiple input conditions including thermal state, vehicle speed, and driver inputs. By adjusting this parameter dynamically according to real-time conditions, the system optimizes stall torque capability while maintaining thermal safety margins
2Measurement precision
If inverter switching frequency is increased to improve torque control precision, then torque control precision is improved, but noise, vibration, and harshness (NVH) performance deteriorates
Solution Approach 1:
The inverter switching frequency is dynamically adjusted based on operating conditions. The controller selects from multiple PWM strategies with different switching frequencies, increasing frequency when precise torque control is needed and decreasing it when NVH performance becomes a concern, thereby balancing both requirements
Solution Approach 2:
The system changes the inverter switching frequency parameter according to real-time operating conditions and selected PWM strategies. By varying this parameter within an optimized range, the system achieves adequate torque control precision while minimizing NVH effects
3Force
If electric stall torque limits are temporarily increased beyond default levels, then stall torque capability is enhanced, but reliability of powertrain hardware may be compromised
Solution Approach 1:
The system implements beforehand cushioning by monitoring thermal conditions and maintaining safety margins before thermal limits are reached. The controller prevents torque limit increases when thermal conditions indicate approaching limits, thereby cushioning against potential hardware damage and maintaining reliability
Solution Approach 2:
The system uses feedback from thermal sensors and operating condition monitoring to continuously adjust electric stall torque limits. Real-time feedback ensures that temporary torque enhancements do not compromise hardware reliability, as the controller responds to thermal state changes and adjusts limits accordingly
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances stall torque capability during low-speed, high-current operations without adverse effects on NVH performance or thermal protection of powertrain components, optimizing electric drive performance in various driving conditions.
Implementation Method 1
Pulse width modulation (PWM)-based switching state control of individual semiconductor switches arranged within switching dies of the power inverter is used to convert a DC input voltage from the battery pack into a polyphase/AC output voltage
Implementation Method 2
The AC output voltage from the power inverter is directed to the stator, and sequentially energizes the stator's field windings to ultimately impart rotation to a rotor
Data Source
AI summary
A method for increasing a default electric stall torque limits in a motor vehicle having an electrified powertrain inclusive of a traction power inverter module (TPIM) connected to an electric traction motor includes receiving vehicle level inputs via a controller. The controller is programmed with the default electric stall torque limits. The method includes selecting an inverter control strategy, via the controller, as a selected inverter control strategy in response to the vehicle level inputs, the strategy including temporarily increasing the default electric stall torque limits while applying a pulse width modulation (PWM) type at a corresponding PWM switching frequency. The method also includes controlling an output state of the TPIM and the electric traction motor over a calibrated duration, via the controller, using the selected inverter control strategy. A motor vehicle includes the controller, road wheels, TPIM, and traction motor.